We're currently on Spark's 80 gig ADSL plan with a landline. I'm considering porting the landline number away to 2Talk but keeping naked ADSL with Spark. From reading a few earlier threads, this sounds as if it might be a little complicated, because porting a Spark landline risks disconnecting the associated broadband at the same time.

I'd like to ask:

(1) What's the best current way to do this without risking lengthy broadband downtime (or disconnection)?

(2) Will Spark charge fees or require a new contract term for going from ADSL + landline to naked ADSL?